diff --git a/w3/BankAccountTest.java b/w3/BankAccountTest.java
new file mode 100644
index 0000000..46dcfe9
--- /dev/null
+++ b/w3/BankAccountTest.java
@@ -0,0 +1,11 @@
+public class BankAccountTest {
+    public static void main(String[] args) {
+        BankAccount account = new BankAccount("6222021234567890123", "张三");
+        account.deposit(1000);
+        account.withdraw(300);
+        System.out.println("户主姓名：" + account.getOwnerName());
+        System.out.println("当前余额：" + account.getBalance());
+        account.setOwnerName("李四");
+        System.out.println("修改后户主姓名：" + account.getOwnerName());
+    }
+}
\ No newline at end of file
diff --git a/w3/bankaccount.java b/w3/bankaccount.java
new file mode 100644
index 0000000..1adefe3
--- /dev/null
+++ b/w3/bankaccount.java
@@ -0,0 +1,46 @@
+public class BankAccount {
+    // 1. 私有属性（封装核心）
+    private final String accountNumber;  // 账号不可修改，用 final 修饰
+    private String ownerName;            // 户主姓名可修改
+    private double balance;              // 余额只能通过存取款修改
+
+    // 2. 构造方法：创建账户时必须提供账号和户主姓名，初始余额为0
+    public BankAccount(String accountNumber, String ownerName) {
+        this.accountNumber = accountNumber;
+        this.ownerName = ownerName;
+        this.balance = 0.0;  // 初始余额固定为0
+    }
+
+    // 3. 存款操作：金额必须大于0
+    public void deposit(double amount) {
+        if (amount > 0) {
+            this.balance += amount;
+            System.out.println("存款成功！当前余额：" + this.balance + " 元");
+        } else {
+            System.out.println("存款失败！存款金额必须大于0。");
+        }
+    }
+
+    // 4. 取款操作：金额必须大于0且不超过当前余额
+    public void withdraw(double amount) {
+        if (amount <= 0) {
+            System.out.println("取款失败！取款金额必须大于0。");
+        } else if (amount > this.balance) {
+            System.out.println("取款失败！取款金额超过当前余额。");
+        } else {
+            this.balance -= amount;
+            System.out.println("取款成功！当前余额：" + this.balance + " 元");
+        }
+    }
+
+    // 5. 查询余额方法（对外提供只读访问）
+    public double getBalance() {
+        return this.balance;
+    }
+
+    // 6. 户主姓名的修改方法（可写）
+    public void setOwnerName(String ownerName) {
+        this.ownerName = ownerName;
+    }
+
+    //
\ No newline at end of file